Antimicrobial mechanisms of g‐C3N4@ZnO against oomycetes Phytophthora capsici: From its metabolism, membrane structures and growth

Backgroud

Phytophthora capsici (P. capsici), a refractory and model oomycete plant pathogen, especially threatens multiple vegetable crops. A limited number of chemical pesticides play a vital role in controlling oomycete plant diseases. However, this approach often leads to excessive use of chemical agent, exacerbates environmental issues and more and more drug‐resistant strains of oomycete. Therefore, it is imperative to devise innovative solutions that can effectively address the infection of oomycete while maintaining high levels of environmental sustainability and low toxicity.

Results

In this study, g‐C₃N₄@ZnO heterostructure was synthesized and characterized. g‐C₃N₄@ZnO showed higher toxicity on P. capsici than g‐C₃N₄ nanosheets and ZnO nanoparticles in vitro and in vivo. Except the hyphal growth of P. capsici, their germination rate of spores, sporangium formation and number of spores were all suppressed by g‐C₃N₄@ZnO heterostructure. Furtherly, we found that this g‐C₃N₄@ZnO heterostructure has higher photocatalytic activity under visible light, which potentially enhanced the reactive oxygen species (ROS) mediated stress on P. capsici. Ultrastructural morphology, global changes of gene expression and weighted gene co‐expression network analysis all supported that the anti‐oomycete activity of g‐C₃N₄@ZnO was manifested in the destruction of membrane system and inhibition of multiple metabolisms of P. capsici under visible irradiation, which also could be attributed to the ROS and Zn²⁺ mediated stress.

Conclusion

This works offers a novel oomycete disease management strategy by using g‐C₃N₄@ZnO, which were attributed to the ROS stress, destruction of membrane system and inhibition of multiple metabolisms.

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